1. Field of the Invention
The present invention relates to fluid flow measurement and, more particularly, addresses overcoming inaccuracies in flow measurement. The invention eliminates errors in mass and volumetric flow rates measured for gaseous fluids with respect to compositional changes in the fluid of interest.
2. Related Art
Hot film microanemometer packages for general use are known for both uni- and bi-directional flow applications. An example of such a device is illustrated and described in U.S. Pat. No. 4,501,144 to Higashi et al. The microanemometers or "microbridges" themselves are quite inexpensive to produce.
As will be described in greater detail below, such microanemometers are capable of quite accurate flow sensing when directly exposed to a stream of fluid flowing past, especially if such flow is laminar. In this manner such a sensor can be used to directly measure the dynamic flow characteristics of the fluid.
While such a sensing system can be used to approximately measure mass flow, a great deal of error has been experienced with respect to changes in composition of the measured fluid in prior devices using the system. Thus, a need has existed for a mass or volumetric flowmeter of the microanemometer class which is less sensitive to changes in the composition of the measured fluid.